Vibration data collection method and apparatus

Abstract

The present invention relates to a vibration data collection method and apparatus. The invention includes processes of receiving electrical vibration signals from at least one vibration sensor, digitizing the electrical vibration signals to obtain digitized vibration signals, calculating the average of the digitized vibration signals over a predetermined period, and storing the average in a storage device. The processes above are repeated to provide a history of averages. When vibration data recording is requested, the invention proceeds to check the history of averages to determine if the averages within a time period are substantially equal to one another within a tolerance. If the averages are within the tolerance, the digitized vibration signals are recorded.

1. A vibration data collection method comprising the steps of:
 receiving electrical vibration signals from at least one vibration sensor; 
 digitising the electrical vibration signals to obtain digitised vibration signals; 
 calculating the average of the digitised vibration signals over a predetermined period; 
 storing the average in a storage device; 
 wherein when data recording is not requested:
 repeating the above steps of receiving, calculating and storing so as to provide a history of averages, and 
 
 wherein when data recording is requested:
 checking the history of averages to determine if the averages within a time period are substantially equal to one another within a first tolerance; and 
 recording the digitised vibration signals if the averages within the time period are substantially equal to one another within the first tolerance. 
 
 
   
   
     2. The method of  claim 1  wherein the at least one vibration sensor is an accelerometer, the digitised vibration signals are digitised acceleration signals, and the history of averages is a history of acceleration averages. 
   
   
     3. The method of  claim 2  further comprising the steps of:
 integrating the digitised acceleration signals to obtain digitised velocity signals; 
 calculating the average of the digitised velocity signals over a predetermined period; 
 storing the average of the digitised velocity signals as a velocity average in a storage device; 
 wherein when data recording is not requested:
 repeating the above steps of integrating, calculating and storing so as to provide a history of velocity averages, and 
 
 wherein when data recording is requested:
 checking the history of velocity averages to determine if the velocity averages within a time period are substantially equal to one another within a second tolerance; and 
 recording the digitised velocity signals if the velocity averages within the time period are substantially equal to one another within the second tolerance. 
 
 
   
   
     4. The method of  claim 3  further comprising the steps of:
 integrating the digitised velocity signals to obtain digitised displacement signals; 
 calculating the average of the digitised displacement signals over a predetermined period; 
 storing the average of the digitised displacement signals as a displacement average in a storage device; 
 wherein when data recording is not requested:
 repeating the above steps of integrating, calculating and storing so as to provide a history of displacement averages, and 
 
 wherein when data recording is requested:
 checking the history of displacement averages to determine if the displacement averages within a time period are substantially equal to one another within a third tolerance; and 
 recording the digitised displacement signals if the displacement averages within the time period are substantially equal to one another within the third tolerance. 
 
 
   
   
     5. The method of  claim 4  wherein, when recording is requested, the method further comprises the step of recording the signals whose history of averages is the first to have values that substantially equal to one another within a tolerance. 
   
   
     6. The method of  claim 5  further comprising the step of recording the signals whose history of averages is next to have values that substantially equal to one another within a tolerance. 
   
   
     7. The method of  claim 3  further comprising the step of recording the digitised velocity signals only once the history of acceleration averages and the history of velocity averages each have values within a time period that are substantially equal to one another within their respective tolerance. 
   
   
     8. The method of  claim 4  further comprising the step of recording the digitised displacement signals only once the history of acceleration averages, the history of velocity averages, and the history of displacement averages each have values within a time period that are substantially equal to one another within their respective tolerance. 
   
   
     9. The method of  claim 4  wherein at least three averages are stored in each of the history of acceleration averages, the history of the velocity averages, and the history of the displacement averages. 
   
   
     10. The method of  claim 4  further comprising the step of recording the signals if a predetermined time-out period has elapsed, even if the averages within the time period are not substantially equal to one another within its tolerance. 
   
   
     11. The method of  claim 10  wherein a different predetermined time-out period is provided for recording each of the digitised acceleration signals, digitised velocity signals and digitised displacement signals. 
   
   
     12. A vibration data collection apparatus comprising:
 at least one input to receive electrical vibration signals from one or more vibration sensors; 
 an analogue-to-digital converter to convert the electrical vibration signals into digital vibration signals; 
 a first averager in communication with the analogue-to-digital converter to the determine an average of the digitised vibration signals over a predetermined period; 
 a storage device in communication with the first averager to store the average determined; and 
 a processor adapted to:
 when data recording is not requested:
 store the average determined by the first averager in the storage device so as to provide a history of averages, and 
 
 when data recording is requested:
 check the history of averages to determine if the averages within a time period are substantially equal to one another within a first tolerance; and 
 record the digitised vibration signals if the averages within the time period are substantially equal to one another within the first tolerance. 
 
 
 
   
   
     13. The apparatus of  claim 12  wherein the vibration sensor is an accelerometer, the digitised vibration signals are acceleration vibration signals and the history of averages is a history of acceleration averages. 
   
   
     14. The apparatus of  claim 13  further comprising:
 a first integrator to convert the acceleration vibration signals into velocity vibration signals; and 
 a second averager in communication with the first integrator to determine an average of the velocity vibration signals over a predetermined period; 
 wherein the processor is further adapted to:
 when velocity data recording is not requested:
 store the average determined by the second averager in the storage device so as to provide a history of velocity averages, and 
 
 when velocity data recording is requested:
 check the history of velocity averages to determine if the velocity averages within a time period are substantially equal to one another within a second tolerance; and 
 record the velocity vibration signals if the velocity averages within the time period are substantially equal to one another within the second tolerance. 
 
 
 
   
   
     15. The apparatus of  claim 14  further comprising:
 a second integrator to convert the velocity vibration signals into displacement vibration signals; and 
 a third averager in communication with the second integrator to determine an average of the displacement vibration signals over a predetermined period; 
 wherein the processor is further adapted to:
 when displacement data recording is not requested:
 store the average determined by the third averager in the storage device so as to provide a history of displacement averages, and 
 
 when displacement data recording is requested:
 check the history of displacement averages to determine if the displacement averages within a time period are substantially equal to one another within a third tolerance; and 
 record the displacement vibration signals if the displacement averages within the time period are substantially equal to one another within the third tolerance. 
 
 
 
   
   
     16. The apparatus of  claim 15  wherein the first, second and third averagers are exponential averagers. 
   
   
     17. The apparatus of  claim 14  wherein the storage device comprises a buffer with a minimum length of three. 
   
   
     18. The apparatus of  claim 14  wherein the processor is adapted to record the signal whose history is first to have values that substantially equal one another within its tolerance. 
   
   
     19. The apparatus of  claim 18  wherein the processor is further adapted to record the signal whose history is next to have values that substantially equal one another within its tolerance. 
   
   
     20. The apparatus of  claim 14  wherein the processor is adapted to record the velocity vibration signals only once the history of acceleration averages and the history of velocity averages each have values that substantially equal one another within their respective tolerances. 
   
   
     21. The apparatus of  claim 20  wherein the processor is further adapted to record the displacement vibration signals only once the history of acceleration averages, the history of velocity averages and the history of displacement averages each have values that substantially equal one another within their respective tolerances. 
   
   
     22. The apparatus of  claim 14  wherein the processor is further adapted to record the vibration signals if a predetermined time-out period has elapsed, even if the history of averages do not have values within a time period that are substantially equal to one another within its tolerance. 
   
   
     23. The apparatus of  claim 22  wherein a different predetermined time-out period is provided for the recording of each of the acceleration vibration signals, velocity vibration signals and displacement vibration signals.